A solid polymer type fuel cell to be mounted on a fuel cell vehicle or the like generates a power by a chemical reaction between hydrogen in a fuel gas supplied to an anode and oxygen in an oxidizing gas supplied to a cathode. In this type of fuel cell, a temperature range optimum for the power generation is usually 70 to 80° C. A long time is sometimes required from a time when the fuel cell is started to a time when this temperature range is reached, depending on a use environment.
In view of such a situation, in a fuel cell system disclosed in Japanese Patent Application Laid-Open No. 2002-313388, a low-efficiency operation is performed to quickly raise the temperature of the fuel cell. Here, the low-efficiency operation is an operation having a large power loss as compared with a usual operation, in other words, an operation of lowering the power generation efficiency of the fuel cell as compared with the usual operation to increase thermal energy as compared with the usual operation. Then, in this fuel cell system, when a cooling solution temperature is 0° C. or less, the low-efficiency operation is constantly performed to reduce the warm-up time of the fuel cell.